(I have similar height and shoulder issues.) It may not seem like it at the back (economy class) but different aircraft are different, and sometimes airlines also lay them out differently from each other. For example look at the Boeing 777 initially released in 1995. At the time economy was laid out 3-3-3. Nowadays most airlines use 3-4-3. That is the difference between a 19 inch wide seat on Singapore Airlines, and a 17 inch wide seat on Emirates.
The aircraft to watch out for the most is the Boeing 787. With one minor exception, they all have one more seat in each economy class row than Boeing originally intended. In general the comment from those of above average height having been on one, is that they will never set foot in a 787 again! The Airbus A350 should be mostly alright on most carriers, but you will need to double check.
A weak rule of thumb is to favour Airbus over Boeing, as their cabin widths and historical choices have tended to result in wider seats in Airbus aircraft. In the US there are efforts to get regulation of seat sizing (under the guise of "safety"), and airlines are trying various things. But someone in the US who is ~1.9m is in the 95th height percentile. It is hard for airlines to cater for that last 5% without a negative economic impact.